We use a third-party sales tax service called Avalara and their AvaTax service. Once a customer enters their shipping info in checkout the add-on connects behind the scenes to get the sales tax rate and the sales tax amount and puts it into the tax value in the cart.
This has been working fine for 3 years.
We recently had no sales for several days. Checked and found lots of abandoned carts. Decided to do test purchase. We get an error that it couldn't connect to the sales tax provider host.
The add-on has a test connection button and we get same connection failed message.
We recently added Sucuri firewall to our GoDaddy hosting (I know, I know). As part of the set up we had to whitelist multiple internal script path files and external URLs for fonts and such. We did whitelist the 3 URLs for the Avatax calculation service but still not working. Any ideas?